Effect of Supplementation of Graded Levels of Organic Zinc on Nutrient Utilization and Retention of Minerals in Broiler Chicken

One hundred and twenty, day old commercial broiler chicks were randomly allotted to 24 replicates with 5 chicks in each and reared for duration of 42 days under uniform and hygienic management conditions to study the effect of supplementing zinc glycinate (Zn-gly) on nutrient utilization and mineral retention. The 24 replicates were randomly allotted to 4 dietary treatments viz., corn soybean basal diets prepared according to NRC recommendation, except Zn (BD) with 40 ppm Zn supplementation from ZnSO₄ (inorganic) and BD with Zn supplemented as Zn-gly (organic) at 30, 20 and 10 ppm. At the end of 42 days, two randomly selected birds per replicate were slaughtered to collect organs (liver, kidney and pancreas) and tibia bone to estimate mineral concentration (Zn, Cu, Mn and Fe). At 35^th day, serum from two birds per replicate was collected for Zn, Cu, Mn and Fe estimation. A metabolic trial was conducted on 2 birds per replicate. Retention of dry matter, organic matter, crude protein, crude fiber, ether extract and nitrogen free extract in broiler chicks was not affected while reducing the Zn supplementation up to 10 ppm as Zn-gly and was comparable to 40 ppm Zn added as ZnSO₄. Replacement of 40 ppm Zn from ZnSO₄ with 30 ppm Zn as Zn-gly increased (P<0.05) Zn retention in kidney and pancreas without any adverse effect on the retention of other minerals. The Zn concentration in liver and tibia of birds was comparable with lower Zn supplementation (10–30 ppm) from Zn-gly than 40 ppm Zn from ZnSO₄. In addition, the Cu content was higher (P<0.01) in the liver and kidney of the birds supplemented with Zn from organic source irrespective of dose compared to 40 ppm Zn from inorganic source. The study indicated that reducing the dietary Zn supplementation by 75% (10 ppm) of recommended levels (40 ppm) using Zn-gly did not adversely affect the nutrient utilization and mineral retention in broiler chicks and 30 ppm Zn from Zn-gly chelate resulted in improved Zn retention in broilers.